A study of the bone machining process--drilling.

Abstract Internal fixation of fractures with screws is a common procedure that has been an historical fact for a number of years. Unfortunately little research has been reported on the action of drilling when preparing for screw insertion. This paper presents some results of a study wherein bovine tibia mid-shaft sections were drilled using several commercially available and experimental drill point geometries under different conditions of feed rate and rotational speed while measuring torque and thrust. Results indicate that drill point geometry is critical when attempting to minimize drilling forces and that there appears to be a softening effect in bone when drilled at relatively high speeds.